The father's tragic final act: He was stabbed to death on his 51st birthday by his 17-year-old son, who also killed his mother and 12-year-old brother in a senseless killing spree.

The tragic final act of a father who was stabbed to death by his 17-year-old son just hours after the family celebrated his 51st birthday has been revealed.

The teenager from Paderno Dugnano near Milan, Italy, also killed his little brother and mother on Sunday.

As has now become known, the boy first hit his twelve-year-old brother in his sleep. His parents, who were woken up by the boy's screams, stormed into the room and were also attacked.

“I stabbed Dad while he was screaming at me to call for help,” the teenager confessed, as reported by Italian news portal Il Difforme.

The boy also told investigators in a chilling way: “There is no real reason why I killed them. I felt like an outsider in my family. Oppressed. I thought I could free myself from this discomfort by killing them all.”

Officers rushed to the family home after the teenager called authorities and told them he had killed his father

According to local reports, the young man initially told authorities a fabricated story that he had seen his father, Fabio Chiarioni, 51, kill his mother, Daniela Albano, 49, and his brother. He then took a knife and stabbed his father to death.

The 17-year-old told investigators that he entered his brother's room on the second floor of the family home and found Chiarioni sitting on a chair with the knife next to him.

He told officers that his mother's body was on the floor at his father's feet and that his brother was found dead in his bed before he attacked his father.

However, the police were not convinced by this story because the boy showed no signs of a struggle on his body and the truth only came to light during a second interrogation.

The teenager told investigators that he felt “uneasy” in his family and that those feelings erupted just hours after the family celebrated Chiarioni's 51st birthday.

He also said he had been thinking about carrying out the murders “for some time,” Il Messaggero reports.

The boy described how he grabbed a large kitchen knife at around two o'clock on Sunday morning, first attacked his little brother and rammed him at least ten times with the weapon.

He then carried out a brutal attack on his brother's parents, who were also in his brother's room. However, the younger brother suffered the most stab wounds.

A 17-year-old boy (pictured below left) slaughtered his entire family early Sunday morning, just hours after they celebrated his father's birthday (pictured above left).

The teenager's mother, Daniela Albano, 49, was found dead in her nightgown in the room of her youngest son, who was also killed

Friends of the family and the mayor of Paderno Dugnano, Anna Varisco, were shocked by the news of the devastating murders

The teenager called authorities immediately after the brutal murders and told Italian emergency services that he had stabbed his father to death.

L'unione Sarda reported that the boy told authorities after the attack: “I killed my father, come.”

When officers arrived at the family's home, they found the 17-year-old lying on the sidewalk in his underwear, his bare back covered in blood.

He is said to have held the blood-soaked knife in his hand until the authorities arrived and then dropped it on the ground.

The officers then found the parents and the brother dead in their nightgowns in the brother's room.

During his confession, he told investigators: “One minute later, it dawned on me. I understood that if I killed her, I would not go free.”

According to a report by the Ansa news agency, the boy has now been arrested for his series of murders after being questioned throughout Sunday by investigators led by Milan juvenile prosecutor Sabrina Ditaranto.

According to judicial sources, the motive for the triple murder is still unclear.

“It will be a long wait before we can explain such a cruel gesture,” they said.

Ditaranto said during a press conference on Sunday: “The boy understood that he had done something irreversible, he expressed his own discomfort that had nothing to do with the family.”

“From a legal point of view, we have no technically valid motive. From a sociological and psychological point of view, the investigation is obviously not yet complete.”

Friends of the family and the mayor of Paderno Dugnano, Anna Varisco, expressed shock at the news of the devastating murders.

“They were a normal, happy family, not being hounded by social services, and described by everyone as having no problems,” Varisco told the outlet.

Neighbors described the family as quiet, wealthy and hardworking people, reports Il Messaggero.

“They were a fantastic, happy family. It's impossible, I don't know what could have happened,” said the father of one of the 17-year-old's classmates.

“He went to school with my daughter, to primary and secondary school, we went on holiday together, I last saw the father a month ago.”

“We have spent some lovely days together in the past.”